The objective of this study was to evaluate the probiotic properties of Lactobacillus casei and Lactobacillus fermentum strains, as well as to select novel and safe strains for future development of functional fermented products. The in vitro auto-aggregation, co-aggregation, hydrophobicity, β-galactosidase production, survival to gastrointestinal tract (GIT), and antibiotic susceptibility were evaluated. The selected strains were additionally tested by the presence of genes encoding adhesion, aggregation and colonization, virulence factors, antibiotic resistance, and biogenic amine production, followed by the evaluation of acidifying kinetic parameters in milk, and survival of the strains under simulated GIT conditions during refrigerated storage of fermented milk. Most strains of both species showed high auto-aggregation; some strains showed co-aggregation ability with other lactic acid bacteria (LAB) and/or pathogens, and both species showed low hydrophobicity values. Seven L. casei and six L. fermentum strains produced β-galactosidase enzymes, and ten strains survived well the simulation of the GIT stressful conditions evaluated in vitro. All strains were resistant to vancomycin, and almost all the strains were resistant to kanamycin. L. casei SJRP38 and L. fermentum SJRP43 were distinguished among the other LAB strains by their higher probiotic potential. L. fermentum SJRP43 presented fewer genes related to virulence factors and antibiotic resistance and needed more time to reach the maximum acidification rate (V). The other kinetic parameters were similar. Both strains survived well (> 8 log CFU/mL) to the GIT-simulated conditions when incorporated in fermented milk. Therefore, these strains presented promising properties for further applications in fermented functional products.
This study aimed at characterizing guava, orange and passion fruit by-products and investigating the effect of adding these fruit by-products to probiotic fermented goat milk and cereal-based fermented products. Fruit byproducts showed total fiber content, phenolic compounds and antioxidant activity varying from, respectively, 58.20-89.80%, 253.14-420.89 mg GAE/100 g, and 11.38-17.37 μmol TE/g. Most carotenoids were represented by β-carotene, which ranged from 7.91 to 56.07 μg/g. The presence of fruit by-products did not affect the fermentation time of fermented oat beverage and fermented goat milk; however, a significant increase (ranging from 0.28 to 0.91 h) in fermentation time of fermented rice beverages was observed after the addition of byproducts. Fruit by-products also resulted in an increase in acidification throughout storage; however, they did not affect the counts of probiotic bacteria. A decrease in probiotic survival during in vitro gastrointestinal simulation was observed in all treatments. Nonetheless, the presence of orange and passion fruit by-products enhanced the resistance of the probiotics to simulated gastrointestinal conditions and resulted in population 2 log CFU/mL higher than the control treatment. Fruit by-products can be considered relevant sources of bioactive compounds useful in raising the functional attributes of probiotic fermented products.
The intestinal microbiota plays an important role in the immune response against viral infections, modulating both innate and adaptive immune responses. The cytokine storm is associated with COVID-19 severity, and the patient’s immune status is influenced by the intestinal microbiota in a gut-lung bidirectional interaction. In this study, we evaluate the intestinal microbiota of Brazilian patients in different post-COVID-19 periods, and correlate this with clinical data and the antibiotic therapy used during the acute phase. DNA extracted from stool samples was sequenced and total anti-SARS-CoV-2 antibodies and C-reactive protein were quantified. Compared with controls, there were significant differences in the microbiota diversity in post-COVID-19 patients, suggesting an intestinal dysbiosis even several months after acute disease resolution. Additionally, we detected some genera possibly associated with the post-COVID-19 dysbiosis, including Desulfovibrio, Haemophillus, Dialister, and Prevotella, in addition to decreased beneficial microbes, associated with antibiotic-induced dysbiosis, such as Bifidobacterium and Akkermansia. Therefore, our hypothesis is that dysbiosis and the indiscriminate use of antibiotics during the pandemic may be associated with post-COVID-19 clinical manifestations. In our study, 39% (n = 58) of patients reported symptoms, including fatigue, dyspnea, myalgia, alopecia, anxiety, memory loss, and depression. These data suggest that microbiota modulation may represent a target for recovery from acute COVID-19 and a therapeutic approach for post-COVID-19 sequelae.
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